(1) Field of the Invention
The present invention generally relates to apparatus and method for controlling a yawing motion variable for an automotive vehicle in which a target yawing motion variable is calculated on the basis of a vehicular running status information such as a vehicular steering angular displacement and a vehicle speed and a feedback control of a yawing motion variable is performed so that the yawing motion variable which is actually developed in the vehicle is coincident with the target yawing motion variable.
More particularly, the present invention relates to the apparatus and method for controlling the yawing motion variable applicable to; a four wheel steering system in which steered angles of respective four wheels are independently and individually controllable; to a driving force control apparatus such as a engagement force controller or a differential limit torque controller of a driving force distribution clutch between front and rear road wheel pairs or between left and right road wheel pairs; to a braking force control apparatus for wheel cylinders disposed for the respective road wheels of the vehicle; to a stabilizer control apparatus in which a roll rigidity between the left and right road wheel pairs is variable; to an active suspension control apparatus; or to a road wheel weight control apparatus in order to enable the feedback control of the yawing motion variable. The yawing motion variable includes a yaw rate.
(2) Description of the Related Art
Each of two previously proposed yawing motion variable controlling apparatuses which is applied to the braking force controlling system is exemplified by Japanese Patent Application First Publications No. Heisei 2-70561 published on Mar. 9, 1990 and Heisei 6-87419 published on Mar. 29, 1994.
In each of these previously proposed yawing motion variable controlling apparatuses disclosed in the above-identified Japanese Patent Application First Publications, a controlled variable is detected as a yaw rate, a target yaw rate is calculated from a vehicular steering angle (angular displacement) and a vehicle speed, a braking force, particularly, a difference in the braking force between a left and right road wheel pair and/or between a front and rear road wheel pair is feedback controlled.
Another previously proposed yawing motion variable controlling apparatus which has been applied to an engagement force controlling apparatus for a driving force distribution clutch between the front and rear road wheel pair or between the left and right road wheel pair is exemplified by a Japanese Patent Application First Publication No. Heisei 3-31030 published on Feb. 8, 1991.
A still another previously proposed yawing motion variable controlling apparatus which has been applied to an active suspension controlling apparatus or to a vehicular stabilizer controlling apparatus, both apparatuses of which enabling a variable control over a rolling rigidity, is exemplified by a Japanese Patent Application First Publication No. Heisei 5-193332 published on Aug. 3, 1993.
A further another previously proposed yawing motion variable controlling apparatus which has been applied to a vehicular braking force controlling apparatus in which braking forces imposed on respective road wheels are independently and individually controlled is exemplified by a Japanese Patent Application First Publication No. Heisei 5-24528 published on Feb. 2, 1993 (which corresponds to a U.S. Pat. No. 5,344,224).
A still further another previously proposed yawing motion variable controlling apparatus which has been applied to a vehicular four wheel steering system is exemplified by a Japanese Patent Application First Publication No. Heisei 8-156816 published on Aug. 18, 1996.